센서회로용 Band-Pass Delta-Sigma Modulator

Abstract

This research presents a band-pass delta-sigma modulator for sensor circuit. We used a periodic driving signal to measure capacitance, and the output of the capacitor varies at the frequency of driving signal. However, there are noise sources to induce a parasitic capacitance, and then the output affects the noise. The noise reducing methods are needed. The band-pass delta-sigma modulator is able to reduce a quantization noise in some band-width and this reducing is controlled by Noise Transfer Function (NTF) of the modulator. We consider that the noise from the sensor elements added to the quantizer input node. This assumption makes the noise controlled by the same NTF. Through this research, the band-pass delta-sigma modulator could use in the sensor circuits by reducing several noise sources in some frequency bands. The reduction increases SNR at the modulator output.